1. Field of the Invention
The present invention relates to digital data processing, and more particularly, to a method of copying encrypted data and an apparatus therefor.
2. Description of the Related Art
Digital data is used in various areas such as digital media, networks, and computing devices. However, since digital data can be copied an infinite number of times without a change in quality, in a communication system such as a computer network and a remote communication system, security and maintenance of digital data is attempted by encrypting digital data, transmitting the encrypted digital data, and allowing only authorized users to use the encrypted digital data. Also, even when digital data is recorded in an information storage medium, digital data is encrypted and recorded so that only the authorized users can use the encrypted digital data.
When data has been encrypted and recorded in a certain storage medium, there exists a case in which the data is copied to another storage medium. If an encryption algorithm and a secret key for the encryption process, used when the data was recorded in the first storage medium, are the same as those of the second storage medium, data to be copied can be read from the first storage medium and recorded in the second storage medium as the data is encrypted. However, in accordance with this method, when the secret key is exposed to other people, the data is vulnerable to hacking. Therefore, to raise the security level of data, unique encryption algorithms are used for each storage medium, or if the same encryption algorithm is used, unique encryption keys are used for each storage medium. In a case where unique encryption algorithms are used for each storage medium (including a case where unique encryption keys are used for each storage medium), a conventional method of copying data between storage media is as follows.
First, after reading corresponding data from a first storage medium storing encrypted data, decrypted data is obtained by applying a decryption algorithm corresponding to an encryption algorithm of the first storage medium to the corresponding data. Next, after encrypting the decrypted data by applying an encryption algorithm of a second storage medium to the decrypted data, the newly encrypted data is recorded in the second storage medium.
In the conventional method of copying data, whenever data is copied, encryption and decryption processes requiring complicated calculations must be performed, and since decrypted, i.e., non-encrypted, data is transferred between storage media, the conventional method is vulnerable to security breaches.